Gemini Trust, the U.S.-based bitcoin exchange founded by investors Tyler and Cameron Winklevoss, on Tuesday opened trading in the U.K., the second leg of an international expansion program.

In an interview last Thursday, Gemini Chief Executive Officer Tyler Winklevoss said that for now, U.K. citizens would only be able to trade online currencies bitcoin and ether on the exchange.

Ether is a token or digital asset of the Ethereum platform, a public blockchain.

Trading bitcoin and ether against fiat currencies such as the dollar and sterling will start in a few weeks, Winklevoss said, adding that no regulatory approval was needed to operate in the UK for the services the company provides.

“The U.K. FCA (Financial Conduct Authority) has made it clear that they’re not regulating digital assets at the moment,” said Winklevoss. “That said, the second that there’s clarity that we have to file something, we will be the first company to file our paperwork.”

Digital currencies have grown in popularity as investors view them as a separate asset class.

Major financial institutions such as Goldman Sachs (GS) and global technology companies such as International Business Machines (IBM) try to unlock the potential uses and applications of these assets’ underlying technology, the blockchain.

The blockchain is a database that enables a network of computers to validate, clear, settle, track, and record the ownership of assets as they are traded.

Volume on Gemini, or the notional value of both bitcoin and ether traded on the platform, for the month of May was approximately $40 million, said Winklevoss.

By the end of June, he sees volume further rising to between $50 million and $60 million.

Bitcoin on Tuesday traded at $677.18 on the Bitstamp platform, with a market capitalization of $10.6 billion, according to crypto-currency data website coinmarketcap.com.

Ether, the second-largest digital currency behind bitcoin, last changed hands at $12.27 and has a market capitalization of nearly $1 billion.